This invention relates to new and useful processes for producing purified anthocyanin colors from plants particularly dark grapes, including known steps to insure discrete monomeric anthocyanin molecules, e.g. treating with sulfur dioxide to decolor and ionize the anthocyanin molecules, and thereafter to use a novel step of ultrafiltration to pass the monomeric anthocyanins through a membrane that retains colloidal impurities of macro-molecular size that have heretofore tended to create haze in color solutions and produce instability thereof.